Dimorphism in methane seep-dwelling ecotypes of the largest known bacteria

We present evidence for a dimorphic life cycle in the vacuolate sulfide-oxidizing bacteria that appears to involve the attachment of a spherical Thiomargarita-like cell to the exteriors of invertebrate integuments and other benthic substrates at methane seeps. The attached cell elongates to produce a stalk-like form before budding off spherical daughter cells resembling free-living Thiomargarita that are abundant in surrounding sulfidic seep sediments. The relationship between the attached parent cell and free-living daughter cell is reminiscent of the dimorphic life modes of the prosthecate Alphaproteobacteria, but on a grand scale, with individual elongate cells reaching nearly a millimeter in length. Abundant growth of attached Thiomargarita-like bacteria on the integuments of gastropods and other seep fauna provides not only a novel ecological niche for these giant bacteria, but also for animals that may benefit from epibiont colonization.     

Stimulation of the lysogenization of Pseudomonas aeruginosa cells by phage transposon B39 induced by plasmid Rms163

The influence of Rms163 plasmid on lysogenization of Pseudomonas aeruginosa cells by B39 phage was studied. Plasmid Rms163 was shown to increase the frequency of lysogenization of PAO1 cells 7-8 times. C-mutants of B39 phage were isolated. According to complementation test, c-mutants were distributed into two groups--cI and cII/III. The product of cI is essential for establishment and maintenance of lysogenic state, cII/cIII product being only necessary for establishment of lysogenization. The mutants with special characteristics were isolated: B39cx1 phage carries a mutation which seems to be located on a regulatory site essential for establishment of lysogenic state. The region of the B39 genome responsible for interaction with Rms163 plasmid was mapped. Possible mechanisms of Rms163 plasmid interference with transposable B39 phage are discussed.     

The effects of pollution on Gammarus pulex (L) subsp,pulex (Schellenberg) in the inlet streams of Rostherne Mere,Cheshire

Two inlet streams, Rostherne Brook and the Southern Drain of Dolls Meadow, flowing into Rostherne Mere, Cheshire were sampled for macroinvertebrata, and their physical and chemical conditions analysed.The physical and chemical factors for these streams were similar, except for the stream beds and the pollution of Rostherne Brook. Both streams had large populations of Gammarus pulex and the life history of this organism was studied. The ratio of adult organism to juvenile diflered in the two streams, Rostherne Brook having a higher proportion of adults in winter and juveniles in summer as opposed to the Southern Drain in which a normal life history was exhibited.Experiments showed that these differences were not related to differences in stream bed conditions. It was considered that the different adult to juvenile ratios were therefore caused by pollution in Rostherne Brook. The juveniles were more tolerant to pollution and therefore more able to survive the summer when pollution effects were at a maximum.The life history was altered in Rostherne Brook by pollution. Instead of the dual life history produced by overwintering juveniles and speedy summer maturation, a simple alternation of juveniles and adults was seen.This change in life history enabled Gammarus to survive in the polluted waters of Rostherne Brook.

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Resume Deux débouchés de ruisseaux, Rostherne Brook et le Southern Drain de Doll's Meadow, qui coulent tous les deux dans le lac de Rostherne dans le Cheshire, ont été échantillonnés pour y trouver des macroinvertébrés, et pour en analyser les conditions physiques et chimiques.On a trouvé semblables les éléments physiques et chimiques de ces ruisseaux, à l'exception du lit des deux ruisseaux et de la pollution de Rostherne Brook.Les deux ruisseaux avaient une population nombreuse de Gammarus pulex dont on a étudié le cycle d'évolution. On a trouvé une proportion différente d'organismes adultes et jeunes dans les deux ruisseaux: Rotherne Brook a une plus grande proportion d'adultes en hiver et de jeunes en été, pendant que Southern Drain montre un cycle normal des organismes.Des expériences ont prouvés que ces différences n'avaient aucun rapport à des différences de conditions du lit des ruisseaux. On a considéré que la pollution de Rostherne Brook a donc causé les proportions différentes d'adultes et de jeunes. Les jeunes toléraient mieux la pollution et pouvaient donc mieux survivre à l'été quand les effets de la pollution étaient au maximum.Le cycle d'évolution était changé dans Rostherne Brook par la pollution. Au lieu du double cycle d'évolution produit par les jeunes qui passaient l'hiver et par un développement rapide en été, on a découvert uniquement l'alternation de jeunes et d'adultes.Ce changement du cycle d'évolution a permis au Gammarus de survivre dans les eaux corrumpues de Rostherne Brook.

     

Purification and characterization of dihydropyridine receptor from rabbit skeletal muscle

Digitonin and 3-[(3-cholamidopropyl)dimethylammonio]-2-hydroxy-1-propane sulfonate (Chapso) were used to solubilize the receptor of dihydropyridine calcium antagonists from the transverse tubule membranes of rabbit skeletal muscle. The receptor retained the ability for selective adsorption from either detergent extract by dihydropyridine-Sepharose. Incubation of the affinity resin with nitrendipine resulted in the elution of the receptor protein composed of two main polypeptides with molecular masses of 160 kDa and 53 kDa, as shown by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Only these two subunits were found in the receptor preparation purified to a specific dihydropyridine-binding activity of 2500-2800 pmol/mg protein (60-70% purity) from digitonin-solubilized membranes by a combination of wheat-germ-agglutinin--Sepharose, anion-exchange and dihydropyridine-Sepharose chromatography steps. The individual subunits were isolated in dodecyl-sulfate-denatured form from the preparation of the receptor, enriched by a two-step large-scale procedure applied to Chapso-solubilized membranes. The 160-kDa subunit slowly changed its apparent molecular mass to 125 kDa upon disulfide bond reduction without formation of novel peptides. This finding implies that 160-kDa subunit is cross-linked by intramolecular S-S bridge(s). Chemical deglycosylation with trifluoromethanesulfonic acid showed that the carbohydrate content of large and small subunits accounted for 7.5% and 6.6% by mass, respectively. The dihydropyridine receptor subunits are glycosylated through N-glycoside bonds only. In their ratio of polar to hydrophobic amino acid residues in the amino acid composition of the receptor subunits, these polypeptides behave rather as peripheral proteins. It is suggested that the main portion of polypeptide chains is located outside the membrane in contact with solvent.     

Cloning of chloroplast psbA and rbcL-genes from cotton Gossipium hirsutum

The fragments of cotton Gossipium hirsutum c.v. 108-f chloroplast genome were cloned in Escherichia coli cells. The cloned psbA and rbcL genes have been selected using the heterologous probes from spinach. The preliminary attempts to clone the complete psbA gene in pUC19 vector failed, probably, due to the toxicity of its product to Escherichia coli cells, and its 5'- and 3'-ends were cloned separately. Reconstruction experiments revealed that while the complete psbA gene was unable to be stably inherited by Escherichia coli cells, its structural part lacking the promoter region could be readily cloned in the bacterial cells.